Methods for percutaneously extending an existing spinal construct

ABSTRACT

Methods and techniques for adding an additional spinal construct in a patient are disclosed. In one arrangement the additional spinal construct extends an existing spinal construct ipsilaterally with an inline rod connector in a minimally invasive or preferably, percutaneous procedure. In another arrangement, the ipsilateral extension of an existing spinal construct uses an offset rod connector for receiving an additional spinal rod that may be placed interiorly or exteriorly of the existing spinal construct.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.13/470,403, filed May 14, 2012, now U.S. Pat. 8,337,532, which claimsthe benefit of U.S. Provisional Application No. 61/568,199, filed onDec. 8, 2011, the contents of which are incorporated in its entiretiesherein by reference.

Background

The present disclosure contemplates methods and techniques for extendingan existing spinal construct, and more particularly to procedures forachieving such extension minimally invasively, and preferablypercutaneously.

An emerging trend in spinal fixation is an increased incidence ofadjacent disc degeneration subsequent to a previous fixation or fusion.This subsequent degeneration often requires fixation or fusion ofadditional levels of the spine. It is common in current techniques toexpose the entire prior construct to access all of the existing bonefasteners to permit removal of the connecting member spanning thefasteners. The connecting member is removed and replaced with a longermember, such as a rod, to engage an additional bone fastener added atthe new levels to be instrumented.

This exposure of the prior fixation construct disrupts the existingconstruct complicating and lengthening the surgical procedure for addingthe additional level of fixation. Such techniques are particularlyproblematic for a fixation construct spanning three or more vertebrallevels. As such, there is a need for a device and method thatfacilitates the addition of further levels of fixation.

Several recent advancements have been disclosed that describe theextension of existing spinal constructs with minimal disruption to theexisting construct. One example is shown in co-pending commonly assignedU.S. application Ser. No. 12/797,682, entitled “Devices and Methods forAdding an Additional Level of Fixation to an Existing Construct”, filedon Jun. 10, 2010 and published as No. 2010/0318131. Other examplesinclude U.S. Pat. No. 7,976,567, entitled “Orthopedic RevisionConnector”, issued on Jul. 12, 2011 to William B. Null, et al. and U.S.Pat. No. 8,021,399, entitled “Rod Extension for Extending FusionConstruct”, issued on Sep. 20, 2011 to Stephen Ritland. While theseapproaches represent improvements in revision techniques and devices, itwould be advantageous to not only extend an existing construct in arelatively non-disruptive manner to such construct, but to do so in aminimally invasively and, preferably percutaneous procedure.

SUMMARY

It is an object of the present invention to provide methods andtechniques for adding an additional construct to an existing spinalconstruct in a patient preferably minimally invasively and morepreferably, percutaneously.

DESCRIPTION OF THE FIGURES

FIG. 1 is a perspective view of a portion of a patient's spine showinginstrumentation disclosed herein to extend an existing ipsilateralspinal construct.

FIG. 2 is a perspective view of a portion of a patient's spine showingan existing spinal construct extended ipsilaterally by one level with anadditional inline spinal construct in accordance with the apparatus ofFIG. 1.

FIG. 3 is an enlarged perspective view of the existing spinal constructand inline extension of FIG. 1.

FIG. 4 is a side view of a rod connector in accordance with onearrangement of the disclosure in a position for attachment to anexisting spinal rod of the existing spinal construct shown in FIG. 3.

FIG. 5 is an end cross-sectional view of the rod connector of FIG. 3engaged to the existing spinal rod.

FIG. 6 is a further view of the rod connector of FIG. 4 showing the rodconnector placed on the existing spinal rod.

FIG. 7 is a further view of the rod connector of FIG. 6 showing the rodconnector partially rotated on the existing spinal rod so as to initiateengagement of the rod connector with the existing spinal rod.

FIG. 8 is a further view of the rod connector of FIG. 7 showing the rodconnector fully rotated and in a final position in engagement with theexisting spinal rod.

FIG. 9 is an end cross-sectional view similar to that of FIG. 5 showingthe securement of the rod connector to the existing spinal rod and thesecurement of an additional spinal rod to the rod connector.

FIG. 10 is an enlarged perspective view of the rod connector extensionassembly attached to the existing spinal rod of the existing spinalconstruct.

FIG. 11 is a perspective view of a patient's spine showinginstrumentation for targeting the position of an existing spinalconstruct within a patient.

FIG. 12 is a perspective view of dilating instruments including anaccess port for use in a percutaneous procedure for extending anexisting spinal construct.

FIG. 13 is a perspective view of the dilating instruments of FIG. 12positioned on existing spinal construct in a patient's spine.

FIG. 14 is a further view of FIG. 13 with the dilating instrumentsremoved and the access port positioned within the patient's spineadjacent the existing spinal construct.

FIG. 15 is a further view of FIG. 14 showing a rod connector extensionassembly attached to an insertion tool in preparation for insertionthrough the access port.

FIG. 16 is a further view of FIG. 15 showing placement of the rodconnector extension assembly into the access port and rotation thereofby the handle of the insertion tool.

FIG. 17 is a further view of FIG. 16 with the insertion tool removed andthe rod connector extension assembly attached to the existing spinal rodwithin the patient's spine.

FIG. 18 is a further view of FIG. 17 showing the placement of a spinalimplant extension assembly through the skin of the patient attaching anadditional spinal implant to an additional vertebral body.

FIG. 19 is a perspective view of a portion of a patient's spine showinginstrumentation disclosed herein to extend an existing ipsilateralspinal construct with an offset additional spinal construct.

FIG. 20 is a further view of FIG. 19 with the extensions removed andshowing an existing spinal construct extended ipsilaterally by one levelwith an offset additional spinal construct.

FIG. 21 is an enlarged perspective view of the existing spinal constructand offset extension of FIG. 20.

FIG. 22 is an end cross-sectional view of the offset rod connector ofFIG. 21.

FIG. 23 is a further view of FIG. 20 showing an access port positionedwithin the patient's spine adjacent an existing spinal construct, theport sized to receive an offset rod connector extension assembly.

FIG. 24 is a perspective view of an additional construct added as across connector to two existing contralateral spinal constructs usingdevices and instrumentation disclosed herein.

FIG. 25 is a posterior view of a portion of the patient's spine showingan additional construct extending an existing spinal construct to afurther bony segment, such as the illium.

DESCRIPTION OF THE EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and described in the following written specification. It isunderstood that no limitation to the scope of the invention is therebyintended. It is further understood that the present invention includesany alterations and modifications to the illustrated embodiments andincludes further applications of the principles of the invention aswould normally occur to one skilled in the art to which this inventionpertains.

Referring to FIGS. 1 and 2, an apparatus 10 is shown for extending anexisting spinal construct 12 by adding an additional spinal construct 14so as to increase the level of spinal fixation in a patient havingpreviously undergone spinal fusion or other spinal surgery. Theapparatus 10 generally comprises a rod connector extension assembly 16,a spinal implant extension assembly 18 and an additional spinal rod 20serving as a connecting element interconnecting the existing spinalconstruct 12 and the additional spinal construct 14. As illustrated, theexisting spinal construct 12 as well as the additional spinal construct14 are located ipsilaterly in the spine in this particular arrangement.As will be described in more detail below, rod connector extensionassembly 16 comprises an elongate extension 22 releasably attached to arod connector 24. Spinal implant extension assembly 18 comprises anelongate extension 26 releasably attached to an additional spinalimplant 28. Each of extension 22 and 26 is sized and of length to beaccessible outside the patient's skin. The patient's skin or fascia isdepicted as a phantom line S for illustrative purposes only, with theunderstanding that the level of the fascia relative to the fixationlocation on the spine will vary from patient to patient. Further shownis a rod introducer 30 that is used to introduce the additional spinalrod 20 into the spinal implant 28 and the rod connector 24 of theadditional spinal construct 14 using a free hand technique. The detailsof rod introducer 30 are fully described in co-pending commonly assignedU.S. patent application Ser. No. 12/818,965 (the '965 Application),entitled “System for Percutaneously Fixing a Connecting Rod to a Spine”,filed on Jun. 18, 2010, the disclosure of which is incorporated hereinby reference in its entirety.

Referring now also to FIG. 3, further details of the additional spinalconstruct 14 and the existing spinal construct 12 are described. Theexisting spinal construct 12 comprises at least two previously implantedbone engaging implants 32 and 34 each of which is engaged respectivelyto a corresponding vertebra 36 and 38. Implants 32 and 34 areinterconnected by an existing spinal rod 40 extending ipsilaterallytherebetween. As shown, each of implants 32, 34 is a polyaxial pediclescrew having a lower threaded fastener portion 33, 35 (FIG. 4) forthreaded engagement respectively in a pedicle of vertebra 36 and apedicle of vertebra 38. Each implant 32, 34 includes a respective upperportion 42 and 44 defines a yoke each having a slot 43, 45 for receiptof the existing spinal rod 40 therein.

The additional spinal construct 14 comprises rod connector 24,additional spinal implant 28 and additional spinal rod 20. Spinalimplant 28, as depicted in FIG. 3, is a polyaxial pedicle screw having alower threaded portion 46 and an upper yoke portion 48 that articulatesrelative to threaded portion 46. The threaded portion 46 is threadedlyengaged to a third spinal segment 50 as will be described. As depicted,spinal segment 50 is sacral segment S1 of the sacrum, it beingunderstood that such spinal segment may be another vertebral body. Theupper yoke portion 48 defines an open ended slot 52 for receipt andsupport therein of one end 20 a of additional spinal rod 20 and isfastened to the yoke portion 48 by a set screw 54 or other suitablefastener. While additional spinal implant 28 is described as being apedicle screw, it should be appreciated that depending upon theapplication additional spinal implant 28 may include other bone engagingimplants with fasteners such as hooks, or rod connectors as will bedescribed below with respect to alternative arrangements.

Rod connector 24 comprises a lower first portion 56 and an upper secondportion 58 articulatingly attached to the first portion 56. The firstportion 56 is attached to the existing spinal rod 40 as will be furtherdescribed. The second portion 58 defines a yoke having an open endedslot 60 for receipt and support therein of the other end 20 b of spinalrod 20 which is fastened to the second portion 58 by a set screw 62 orother suitable fastener. As illustrated in FIG. 3 the additional spinalconstruct 14 is considered to be inline with the existing spinalconstruct 12. In such an arrangement, the upper second portion 58 of theconnector 24 is positioned above and generally in alignment with theaxis of the existing spinal rod 40. The additional spinal rod 20 ispositioned above bone engaging implant 34 with the axis of additionalspinal rod 20 aligned generally parallel with the axis of the existingspinal rod 40. As such, the existing spinal rod 40 and the additionalspinal rod 20 are spaced approximately the same distance from a mid-lineplane through the spine of a patient. It should be appreciated thatdepending upon the anatomy the additional rod 20, while projecting abovethe existing rod 40, may not be parallel thereto.

Turning now to FIGS. 4 and 5, further the details of the rod connector24 are described. The second portion 58 of the rod connector has a firstsection 58 a and a second section 58 b as shown in FIG. 5. First section58 a comprises a pair of opposed upstanding arms 64 and 66 that define ayoke having slot a 60. The lower end of the second section 58 b isprovided with a generally spherically shaped surface 68 for articulatingmovement on a similarly generally spherically shaped surface 70 formedon an interior surface of the first portion 56 as also seen in FIG. 5.Section 58 a is attached to section 58 b to constrain rotationalmovement but to allow slight axial movement therebetween. Thearticulating movement allows the first portion 56 and the second portion58 to swivel and rotate with respect to each other between surfaces 68and 70 when in an unlocked position. The upstanding arms 64 and 66cooperatively define threads 72 for threaded receipt therein of setscrew 62. A locking screw 74, retentively retained in the second portion58, includes an upper head 76 and a lower portion 78. The lower exteriorsurface 80 of the head 76 is generally spherical to allow thearticulating movement between the first and second portions 56, 58 asouter surface 80 engages spherically shaped interior surface 82. Thehead 76 is also provided with an interior socket 84 that is configuredin a hex pattern or other suitable shape, such as a conventional Torxconfiguration, to engage a similarly configured feature on an innershaft of an insertion tool for placement of the rod connector 24 on theexisting spinal rod 40. The lower portion 78 of the locking screw 74 isthreaded for threaded engagement with threads 85 extending through theupper end of the first portion 56 to permit engagement of the lockingscrew 74 with the existing spinal rod 40, as will be described.

With reference still to FIGS. 4 and 5, the lower end of the firstportion 56 of rod connector 24 comprises a pair of spaced hooks 86 and88 each of which includes a respective projecting rod engagement member90. Hooks 86 and 88 are spaced from each other at a distance defining anopening 92 that allows the existing rod 40 to be received therebetween.In the position as shown in FIG. 5 the rod connector 24 is in anunlocked position whereby rod connector 24 may rotate about the axis ofthe existing spinal rod 40 and first portion 56 and second portion 58 ofthe rod connector 24 may relatively articulate.

With reference to FIGS. 6 through 8, the operation of the rod connector24 during attachment to the existing spinal rod 40 is described. In FIG.6 the rod connector 24 is shown as being placed between the existingimplants 32 and 34 with the existing spinal rod 40 received in theopening 92 between hooks 86 and 88. In this position, the rod engagementmembers 90 are not in engagement with spinal rod 40 but straddle theexisting rod 40. As shown in FIG. 7, the rod connector 24 is rotatedabout axis 94 to cause engagement between the rod engagement portions 90and the existing spinal rod 40. Rotation of the rod connector 24 iseffected by rotation of the insertion tool 126 (FIG. 15) that is engagedto the rod connector 24 in part by way of the locking screw 74. Theinsertion tool 126 applies pressure to section 58 b of the secondportion 58 which in turn applies pressure to first portion 56. Thispressure draws first section 58 a axially upward such that sphericalsurfaces 80 and 82 as well as spherical surfaces 68 and 70 are engaged.As such, when the insertion tool 126 is rotated the entire rod connector24 is rotated. FIG. 8 shows completion of the rotation of the rodconnector 24 with the engagement members 90 being in engagement with theexisting spinal rod 40 and ready for secured attachment thereto.

Once the rod connector 24 has been rotated to the appropriate attachmentposition, the rod connector 24 is in position for receipt of theadditional rod 20 and for securement to the existing spinal rod 40 asshown in FIG. 9. Before the additional rod 20 is received in the rodconnector 24, the locking screw 74 is tightened by an inner shaft 129supported within a housing 126 a of the insertion tool 126, the innershaft 129 terminating at its proximal end at handle 130 (FIG. 15). Theinner shaft 129 and handle 130 rotate independently of housing 126 a.The lower end 96 of the locking screw 74 engages the existing spinal rod40 and thereby fixedly secures the first portion 56 of the rod connector24 to the existing rod 40. In this stage, the second portion 58 of therod connector 24 is still allowed a certain degree of angular movementand rotation with respect to the first portion 56 by interaction betweenspherical surfaces 80 and 82 as described above. This allows forirregularities of the spine and further manipulation of the secondportion 58 of rod connector 24 for proper receipt of additional rod 20.Once the additional rod 20 placed in the slot 60 of rod connector 24,the set screw 62 is then inserted and threaded into the threads 72 ofthe rod connector 24. Tightening of set screw 62 by a suitablescrewdriver causes the lower end 98 of the set screw 62 to engage theadditional spinal rod 20 which in turn engages an upper interior surface58 c of second section 58 b. This causes the second section 58 b toengage first portion 56 thereby locking spherical surfaces 68 and 70while pulling first section 58 a upwardly against locking screw 74thereby locking spherical surfaces 80 and 82. Thus, the first and secondrod connector portions 56 and 58 are locked together and the existingspinal rod 40 and the additional spinal rod 20 are secured in a fixedlocked position with respect to each other.

Turning now to FIG. 10, the details of the rod connector extensionassembly 16 are described. The rod connector assembly 16 compriseselongate extension 22 that is releasably attached to the second portion58 of the rod connector 24. Extension 22 comprises an elongate sleeve100 that has a lumen 102 extending lengthwise through the sleeve 100 incommunication with rod connector 24. The sleeve 100 includes a pair ofopposed axially extending slots 104 that extend through the wall ofsleeve 100 and communicate with the lumen 102. The slots 104 openthrough the distal end 106 of the sleeve 100 such that when the sleeve100 is releasably attached to the rod connector 24 the slots 104 arealigned in communication with slot 60 in the second portion 58 of therod connector 24.

Referring also to FIG. 1, the sleeve 100 of extension 22 has a proximalend 108 with a length of the sleeve being defined between the distal end106 end the proximal end 108. The length is of such dimension such thatwhen the rod connector 24 is placed through the skin S and approximatesthe position of the existing spinal rod 40, the proximal end 108 extendsoutside the patient whereby the proximal end 108 may be manipulated toattach the rod connector 24 to the existing spinal rod 40. The slots 104extend axially toward the proximal end 108 for a portion of the lengthof the sleeve 100 such that the slots 104 also extend outside thepatient when the distal end 106 of the sleeve 100 is secured to the rodconnector 24. When the sleeve 100 is releasably secured to the secondportion 58 of the rod connector 24 the sleeve 100 and the second portion58 jointly move in common. As such, manipulation of the sleeve 100allows for angular and rotational manipulation of the second portion 58,particularly in the stage after the first portion 56 has been fixedlysecured to the existing spinal rod 40 by tightening of the locking screw74 and prior to the placement of the additional spinal rod 20. Selectiveorientation of the slots 104 as well as positioning of the secondportion 58 to a location best suited for receipt of the additional rod20 can be achieved. The particular details of the extension 22 includingthe structure of the sleeve 100 and the method of releasably securingthe sleeve 22 to the rod connector 24 are described fully in the '965Application incorporated herein by reference in its entirety.

Having described the devices and instruments for extending an existingspinal rod construct in a patient, the procedures for such extension arenow described with particular reference to FIGS. 11-18. The firstprocedure relates to percutaneously extending an existing spinalconstruct 12 as shown in FIG. 11 with an inline ipsilateral additionalconstruct as described above. Using fluoroscopy or other suitableimaging techniques, the existing spinal rod 40 is initially targeted soas to establish the position of the existing rod 40 in the patient. Asmall first percutaneous incision 110 is made through the skin S of thepatient, the incision 110 being approximately 10-20 mm in length,although other suitable dimensions may be used. A targeting rod 112 isplaced through the incised puncture and pushed through the tissue of thepatient down to the existing spinal rod 40. Once the access path hasbeen created and the position of the existing rod 40 established aseries of sequentially increasing dilating instruments are inserted overthe targeting rod 112. As depicted in FIG. 12, the dilating instrumentsinclude an initial split dilator 114 that attaches temporarily to theexisting rod 40, and dilating cannulas 116 and 118 of increasingdiameter. The number of dilating cannulas may vary depending upon theprocedure and the desired extent the incision 110 is to be expanded upondilation. An access port 120 is then finally placed over the lastdilating cannula 118, the access port 120 having a pair of opposednotches 122 that receive the rod 40 as shown in FIG. 13. The dilatinginstruments are then removed as illustrated in FIG. 14 leaving theaccess port 120 in place. The central longitudinal axis of the accessport 120 is generally aligned with and perpendicular to the longitudinalaxis of existing rod 40. A bracket 124 may be utilized to fix the accessport 120 to the operating table so as to maintain the access port 120 inplace throughout the surgical procedure. The proximal end 120 a of theaccess port 120 projects out from the patient's skin S as shown in FIG.14.

A rod connector extension assembly 16, including a rod connector 24 andan extension sleeve 100 as described above with respect to FIG. 10, ismated with an insertion tool 126, as shown in FIG. 15. The insertiontool 126 comprises outer housing 126 a supporting inner shaft 129 thatterminates at proximal end 128 of the tool 126 in rotatable handle 130.The distal end (not shown) of the inner shaft 129 has an engagementfeature in engagement with the shaped socket 84 in the locking screwhead 76. The insertion tool 126 includes a locking mechanism 132 forinitially holding the first portion 56 and the second portion 58 of therod connector 24 in a fixed rotational position while the inner shaft129 and handle may freely rotate. The housing 126 a, based on itsconfiguration or other suitable reference marks, may be oriented to bealigned with the opening 92 between the hooks 86 and 88 of the rodconnector 24 so that the opening 92 can be located with respect to therod 40 by the positioning of the tool 126 during insertion of the rodconnector extension assembly 16.

Rod connector extension assembly 16 is then introduced through theaccess port 120 by the manipulation of the extension sleeve 100 andinsertion tool 126 from outside the patient until the rod 40 is receivedin the opening 92 between hooks 86 and 88 as shown in FIG. 6. The toolhousing 126 a is rotated clockwise as shown by arrow 134 in FIG. 16approximately 90° to thereby rotate the rod connector 24 in a mannerthat causes engagement of the rod engagement members 90 with theexisting spinal rod 40 and moving hooks 86, 88 to the position shown inFIG. 8. During rotation of the rod connector 24, the sleeve 100 is alsorotated in common until the opposing slots 104 are aligned generallycoaxially with the longitudinal axis of the existing spinal rod 40. Asthe distal end of the inner shaft 129 of the insertion tool 126 isengaged with the socket 84 of the locking screw 74, rotation of thehandle 130 causes threaded rotation of the locking screw 74 to therebytighten and lock the first rod connector portion 56 to the spinal rod 40in the stage as shown in FIG. 9 as described above. The insertion tool126 and the access port 120 are then removed leaving the rod connectorextension assembly 16 in place with the rod connector 24 attached to theexisting spinal rod 40 as shown in FIG. 17. As noted hereinabove, acertain degree of angulation and rotation of the rod connector secondportion 58, as well as the extension sleeve 100 attached thereto incommon movement therewith, is permitted with respect to the rodconnector first portion 56. The rod connector 24 is thereby insertedthrough the access port 120 and attached to the existing rod 40 in a toploading procedure without disturbing the existing implants 32 and 34 orthe previous connections to the existing rod 40. The top loading allowsa surgeon to insert the rod connector 24 and connect it to the existingrod 40 from above the spine facilitating the percutaneous procedure.

Turning now to FIG. 18, the engagement of the additional spinal implant28 as a component of the additional spinal rod construct 14 isdescribed. Spinal implant extension assembly 18 comprises secondelongate extension 26 which includes a second sleeve 136 releasablysecured to the additional spinal implant 28. Spinal implant 28 isdescribed as noted above with reference to FIG. 3 as being a polyaxialpedicle screw in this arrangement. Sleeve 136 has a pair of opposingslots 138 extending therethrough, the slots 138 being aligned and incommunication with the slot 52 in the upper yoke portion 48 (see FIG. 3)of the spinal implant 28. The additional spinal implant 28 ispercutaneously attached to the pedicle of sacral segment S1 of thesacrum 50 through a small second percutaneous incision 140 made throughthe skin S of the patient, separate and apart from the first incision110. The incision 140 is approximately 10-20 mm in length. The dilationof incision 140 and the percutaneous attachment of spinal implant 28 toa spinal segment such as sacrum 50 is fully described in the '965Application. Once spinal implant 28 is attached to the sacrum 50 thesecond sleeve 136 as well as slots 138 project out from the patientthrough dilated incision 140 with the slots 138 being rotatablymanipulable upon rotation of sleeve 136 to be aligned with slots 104 ofextension 22 as shown in FIG. 18.

With the rod connector 24 being attached to existing spinal rod 40 andwith additional spinal implant 28 being attached to the third spinalsegment such as sacrum 50, the additional spinal rod 20 is now ready tobe implanted. Referring back now to FIG. 1 elongate extensions 22, 26project outwardly from the patient's skin S with the slots 104 and 138of the respective extensions 22 and 26 being oriented in substantialalignment with each other. As such, the slot 60 in the rod connectorsecond portion 58 and the slot 52 in the yoke portion 48 of the spinalimplant 28 are likewise in alignment. The additional spinal rod 20 issuitably attached adjacent end 20 a to the rod introducer 30 in a mannerthat permits pivotal movement of the rod 20 relative to the introducer30.

Rod 20 is then introduced in this procedure through incision 140 at anextreme cephalad or caudal location of the spinal implant extensionassembly 18. Alternatively, the rod 20 may be introduced throughincision 110 instead of incision 140. In the approach using incision140, the rod 20 is oriented at a 45° angle relative to the shaft 142 ofthe rod introducer 30. The introducer 30 is manipulated by hand so thatthe leading end 20 b of the rod 20 passes through slots 138 of thespinal implant extension assembly 18 and subsequently or simultaneouslythrough incision 140. If necessary, the angle of the rod 20 may beadjusted to facilitate entry of the rod 20 through incision 140.

Once below the skin surface S the rod 20 can be advanced subcutaneouslybeneath the fascia toward the rod connector extension assembly 16. Thesides of the slots 138 in extension sleeve 136 further act as guides tokeep the rod 20 aligned during subcutaneous advancement until the rod 20enters slots 104 of the rod connector extension assembly 16. Rod 20 maythen be seated into slot 60 of rod connector 24 and slot 52 of spinalimplant 28 by manipulation of the rod introducer 30 or by a suitable rodpersuader (not shown). Once the rod 20 is fully seated in the rodconnector 24 and the spinal implant 28, rod introducer may be disengagedfrom end 20 a. Set screw 54 may then be inserted through extension 26 bya suitable driver to engage the threads of yoke 48 to secure end 20 a tospinal implant 28. Similarly, set screw 62 may then be inserted throughextension 22 by a suitable driver to engage the threads of secondportion 58 of the rod connector 24 to secure end 20 b to the rodconnector 24. Extensions 22 and 26 may then be released respectivelyfrom rod connector 24 and spinal implant 28 and the incisions 110 and140 suitably closed. As such, the inline ipsilateral extension of theexisting spinal construct 12 by additional spinal construct 14 as shownin FIG. 3 is complete. Further details of the subcutaneous rodplacement, rod persuasion and securement of the rod to the spinalimplant 28 and rod connector 24 are described in the '965 Application

In the procedure just described, additional rod 20 is introducedexteriorly of the extension assemblies through an incision in commonwith an extension assembly using only two incisions, namely incisions110 and 140. In an alternative procedure, the rod 20 may be introducedinto the surgical site through a third separate incision as fullydescribed in the '965 Application. The free hand rod introducer 30 maybe used to place rod 20 for implantation through the third separateincision. It should be appreciated, however, that non-free handinstruments that may be attached to one or both of the spinal implantextension assembly 18 and the rod connector extension assembly 16 wherethe third separate incision approach is desired. Such instruments, forexample, are shown and described in U.S. Pat. No. 6,530,929, entitled“Instruments for Stabilization of Bony Structures”, issued on Mar. 11,2003 to Justis, et al., the disclosure of which is incorporated hereinby reference in its entirety.

In another procedure a single incision may be used to provide the inlineextension of an existing spinal construct. In this minimally invasiveapproach, a common incision may be formed joining the separate incisions110 and 140 through which the rod connector extension assembly 16 andthe spinal implant extension assembly 18 have been respectivelyintroduced thereby forming a single incision. Alternatively, a singleincision may be initially made through the skin S through which the rodconnector extension assembly 16 and the spinal implant extensionassembly 18 may be introduced. While such a single incision approach maynot be regarded as percutaneous, it is considered a minimally invasivesurgical approach. Once inserted through such a single incision wherebythe rod connector 24 is attached to existing spinal rod 40 andadditional spinal implant 28 is secured to a third vertebral body 50,the respectively attached extensions 22 and 26 project outwardly fromthe patient through the single incision. Slots 104 and 138 in theextensions may then be oriented in a manner such that the slots arealigned in a facing orientation. The additional rod 20 may be introducedby rod introducer 30 exteriorly of either one of the extensions 22 and26 but through the single incision as described above using slots 104and 138 as guides. Such approach is further fully described in the '965Application

Alternatively, with the single incision approach, additional rod 20 maybe introduced through the single incision between the extensions 22 and26. With the slots 104 and 138 and the extensions extending outside thepatient and oriented to face each other, a suitable rod holder may beused to place opposite ends of rod 20 into slots 104 and 138 and movethe rod 24 toward the patient and through the single incision until therespective ends of the rod 20 are seated respectively in rod connector24 and spinal implant 28. Rod holding instruments and techniques forthis approach, for example, are shown and described in U.S. Pat. No.7,491,218, entitled “Spinal Stabilization Systems and Methods UsingMinimally Invasive Surgical Procedures”, issued on Feb. 17, 2009 toLandry, et al., the disclosure of which is incorporated herein byreference in its entirety. In a variation using the single incisionapproach, the slots 104 and 138 may be formed each as a single slotthrough the wall of the extension sleeves 100 and 136 rather than as apair of opposing slots, as described above. The length of such singleslots 104 and 138 are likewise of extent to extend outside the patientwhen the respective extensions are in place in the patient. The singleslots 104 and 138 are then arranged in facing orientation to receive therespective opposite ends of the rod 20 between the extensions 22 and 26serving as guides for movement of the rod 20 through the single incisionfor seating in the rod connector 24 and the spinal implant 28.

While the existing spinal construct 12 has been described herein asbeing extended by a single level, it should be appreciated that theextension may comprise two or more levels with the devices andinstruments set forth herein. In addition, while the devices andinstruments described herein provide surgeons the ability to extendexisting spinal constructs at least minimally invasively and morepreferably, percutaneously, it should be understood that a surgeon mayalso use the described devices and instruments in an open procedure ifthat is the surgeon's surgical preference.

Having described the ipsilateral inline extension of an existing spinalconstruct hereinabove, devices and instruments for ipsilateral offsetextension are now described with reference to FIGS. 19-23. The offsetextension may be implanted in the same fashion as the inline extension,namely percutaneously, minimally invasively or, if the surgeon choosesin an open procedure.

As depicted in FIGS. 19-20, the existing spinal construct 12 is extendedby an additional offset spinal construct 144 comprising an offset rodconnector 146, additional spinal rod 20 and additional spinal implant28. Additional spinal implant 28, as described above, is releasablyattached to extension 26 including sleeve 136, implant 28 and extension26 comprising the spinal implant extension assembly 18. Sleeve 136 hasopposing slots 138 extending therethrough. Spinal implant extensionassembly 18 is identical to that described above regarding the inlineextension and the spinal implant 28 is implanted in the same manner.

Offset rod connector 146 is releasably attached to an elongate extension148 comprising a sleeve 150. Offset rod connector 146 and extension 150comprise an offset rod connector extension assembly 152. Sleeve 150 hasopposing slots 154 extending therethrough. Extensions 26, 150 and theirrespective slots 138, 154 extend outwardly from the skin of the patientas described above when the extension assemblies 18, 152 are attached tothe spine.

Turning now to FIGS. 21-22, the details of the offset rod connector 146are described. Rod connector 146 comprises a first portion 156 and anoffset second portion 158 supported by a support member 160. Secondportion 158 is configured to be laterally offset from first portion 156when the offset rod connector 146 is secured to existing spinal rod 40.First portion 156 is retentively supported by support member 160 withina throughhole 162 for rotational movement therewithin. First portion 156comprises a pair of opposing spaced hooks 164 and 166 defining anopening 168 therebetween for receipt of existing spinal rod 40. Eachhook 164, 166 has a projecting rod engagement member 170 for engagementwith additional rod 20 as the first portion 156 is rotated relative tothe support member 160 during insertion similar to rod connector 24described above. A threaded interlocking screw 172 is threadably rotatedwithin first portion 156, the locking screw 172 including an internalsocket 174 for use in rotating and thereafter locking the first portion156 to additional rod 20 by an insertion tool. An outer internallythreaded nut 176 is provided to lock the first portion 156 to thesupport member 160.

Second portion 158 is retentively supported by the support member 160for swivel movement through the interfacing of inner spherical surface178 on support member 160 and the outer spherical surface 180 on aninsert 182 threadably attached to a yoke 184. As such, second portion158 also articulates relative to the first portion 156. Yoke 184comprises a pair of opposing upstanding arms 186 and 188 defining a slot190 therebetween for receipt of additional rod 20. The arms 186 and 188include internal threads 192 for receiving a set screw 194 (FIG. 21) forsecuring additional rod 20 to the yoke 184 of second portion 158 upontightening. Tightening of set screw 194 also locks the second portion158 to support member 160 and thereby to the first portion 156. Thestructure and operation of the locking of additional rod 20 to yoke 184and yoke 184 to the support member 160 are similar to that disclosed inco-pending commonly assigned U.S. application Ser. No. 11/560,587,entitled “Multi-axial Spinal Fixation System”, filed on Nov. 16, 2006and issued as U.S. Pat. No. 8,162,990, the disclosure of which isincorporated herein by reference in its entirety.

The procedure for attaching the offset rod connector 146 by manipulationof the offset rod connector extension assembly 152 to the existingspinal rod 40 is substantially the same as the attachment of the inlinerod connector 24 by the rod connector extension assembly 16 as describedabove. An incision 196 is initially formed through the skin S, similarto incision 110, as shown in FIG. 23. The incision 196 is enlargedradially and laterally for insertion of an oval access port 198 similarto access port 120 but sized and configured to receive the offset rodconnector assembly 152 therethrough for introduction of the offset rodconnector 144 to the spine. The remainder of the procedure proceedsgenerally thereafter as described above.

In the completed offset additional spinal construct 144 as shown inFIGS. 21-22, the additional rod 20 is located laterally father away fromthe midline of the patient then the existing spinal rod 40. In analternative arrangement, the offset rod connector 146 may be installedwith the yoke 184 located interiorly of the existing spinal construct 12such that the additional rod lies closer to the midline of the patient.The offset additional spinal construct 144 may also present a lowerprofile than the inline arrangement since the additional rod 20 does notlie above the existing construct illustrated in FIG. 1.

Turning now to FIG. 24, a further application of the devices andinstruments of the subject disclosure is shown. Heretofore, theadditional constructs have been added to existing spinal constructsipsilaterally. In the application shown in FIG. 24, an additional spinalconstruct in the form of a cross connector 200 is added to a pair ofexisting contralateral spinal constructs 202 and 204 disposed ondifferent sides of the spine each being offset from the spinal midlineplane. Spinal constructs 202 and 204 are existing in the sense that theyhave been installed prior to the installation of the cross connector 200even though the cross connector 200 may be placed during the samesurgical procedure.

Existing spinal construct 202 is identical to existing spinal construct12 described above and comprises at least two bone engaging implants 206and 208 each of which is respectively engaged to a correspondingvertebra 210 and 212. Implants 206 and 208 are interconnected by aspinal rod 214 extending therebetween, implants 206 and 208 each beingshown as a polyaxial pedicle screw. The other existing construct 204 isalso identical to existing spinal construct 12 and comprises at leasttwo bone engaging implants 216 and 218 each of which is respectivelyengaged to the same corresponding vertebrae 210 and 212, except on theopposite side of the midline of the spine. Implants 216 and 218 are alsoshown as being polyaxial pedicle screws which are interconnected by aspinal rod 220.

In a percutaneous procedure, the spinal constructs 202 and 204 areinstalled percutaneously in accordance with the devices, instruments andtechniques described in the aforementioned '965 Application which hasbeen incorporated herein by reference in its entirety. As such, implants206 and 208 may each be implanted through a separate incision withinterconnecting rod 210 being placed subcutaneously therebetween.Implants 216 and 218 may likewise be implanted percutaneously throughseparate incisions with interconnecting rod 220 similarly being placedsubcutaneously therebetween.

In accordance with the subject technique, a spinal implant such as rodconnector 222 may then be attached to an existing rod 214 and a spinalimplant such as rod connector 224 may be attached to existing rod 220.Rod connectors 222 and 224 are each identical to the rod connector 24described above with respect to the inline extension. Each of rodconnectors 222, 224 is attached to respective rods 214 and 220 using arod connector extension assembly identical to rod connector extensionassembly 16, employing the same targeting, dilation and insertionprocedures as described above with respect to the inline extension. Oncethe rod connector extension assemblies have been attached to therespective existing rods 214 and 220 and the respective extensionsproject outwardly from the patient, the additional spinal construct 200,such as a solid spinal rod, may be placed subcutaneously contralaterallybetween rod connectors 222 and 224 and secured thereto in accordancewith the procedures of the '965 Application. In such a percutaneousprocedure, three separate incisions may be formed on each side of thespine for a total of six small incisions. On each side of the spine twoincisions may be used respectively for each of the pedicle screws andone incision for a rod connector 222 or 224. In a minimally invasiveprocedure, two common incisions may be formed on each side of the spine.Each common incision may be of such length so as to receive a pair ofpedicle screws (206, 208 or 216, 218), an interconnecting rod such (214or 220) as well as a rod connector (222 or 224) each of which isattached to a rod connector extension assembly. With an extension ofeach rod connector extension assembly projecting outwardly from thepatient the cross connector rod 200 may then be placed subcutaneouslybeneath the skin between the contralateral common incisions tointerconnect the rod connectors 222 and 224 in accordance with theprocedures of the '965 Application. Thus, in the minimally invasiveapproach, a total of two common incisions may be formed on each side ofthe spine.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same should be considered asillustrative and not restrictive in character. For example, the existingspinal constructs described hereinabove are attached to the spinalsegments such as adjacent vertebral bodies that may be extended with anadditional spinal construct caudad to the sacrum or cephalad to one ormore additional vertebral bodies. Variations are contemplated thatinclude an additional construct that extends an existing spinalconstruct from spinal segments to other bony segments, which may bewithin the spine, such as vertebral bodies or the sacrum, or outside thespine, such as the Ilium. As shown in FIG. 25, an existing spinalconstruct 226 comprises a pair of bone engaging implants such asfasteners 228 and 230 and an existing spinal rod 232. Bone fastener 228is a pedicle screw threadably secured to vertebral body 234, which asshown is lumbar segment L5. Bone fastener 230 is a pedicle screwthreadably secured to the pedicle of the sacrum 236, which is shown assacral segment S1. The existing rod 232 is inserted and attached to thebone fasteners 228 and 230 as described hereinabove. In thisarrangement, rod 232 may have a length such that insertion end 232 a hasan extent projecting beyond bone fastener 230 toward the sacrum. Whilein the arrangements previously described an extent of the existing rodextending between bone fasteners is targeted for connection to a rodconnector, in the arrangement of FIG. 25 the projecting rod end 232 a istargeted. As such, a rod connector 238 similar to previously describedrod connector 24 is attached to rod end 232 a with a releasable rodconnector extension assembly similar to rod connector extension assembly16. Third bone engaging implant 240 such as an iliac screw similar tospinal implant 28 is threadably secured to the Ilium 242 with areleasable bone implant extension assembly similar to spinal implantextension assembly 16. Additional rod 244 similar to additional rod 20is then attached to rod connector 238 and iliac screw 240 in a manner asdescribed hereinabove to form the additional construct 246. Asdescribed, the procedure may be percutaneous, minimally invasive or anopen procedure.

It is understood that only the preferred embodiments have been presentedand that all changes, modifications and further applications that comewithin the spirit of the invention are desired to be protected.

1-7. (canceled)
 8. A method of percutaneously extending an existingspinal construct implanted in a patient having at least two boneengaging implants engaged to corresponding spinal segments andinterconnected ipsilaterally by an existing spinal rod, comprising thesteps of: targeting the existing spinal rod to establish an attachmentlocation of said existing rod in said patient at a location other thanat the location of either of said at least two bone engaging implants;creating a percutaneous access path through the tissue of said patientto said existing spinal rod based on the established attachment locationof said existing rod position; and percutaneously attaching through saidaccess path a rod connector to said existing spinal rod at saidattachment location, said rod connector having a first portion forengagement with said existing spinal rod and a second portionarticulatingly attached to said first portion, said first portionincluding thereon a projecting rod engagement member rotatable with saidfirst portion, said rod engagement member being configured to engage theopposite underside of said existing spinal rod upon rotation thereofwith said first portion, and wherein said entire first portion isrotated to place said rod engagement member in engagement with saidexisting spinal rod at the underside thereof, said second portion beingreleasably secured to an elongate extension, said rod connector beingmanipulated through said access path by said extension to engage saidexisting spinal rod.
 9. The method of claim 8, wherein said targetingstep includes using an imaging technique to determine the position ofsaid existing spinal rod.
 10. The method of claim 9, wherein saidcreating step includes the step of making a small incision through theskin of the patient to access said existing spinal rod.
 11. The methodof claim 10, further including the step of expanding said incision byplacing in said incision a series of sequentially increasing dilatinginstruments.
 12. The method of claim 11, including the step of placingan access port over the last placed dilating instrument, the access porthaving a distal end and a proximal end and a length defined by a centrallongitudinal axis extending therebetween, the distal end being placedadjacent said existing spinal rod such that said central longitudinalaxis is generally aligned with an substantially perpendicular to thelongitudinal axis of the existing spinal rod, a proximal end projectingoutwardly from the skin of said patient.
 13. The method of claim 12,wherein said percutaneously attaching step includes introducing saidelongate extension and said rod connector through said access port froma top loading position, placing said rod connector adjacent to an upperside of said existing spinal rod at said attachment location, andengaging said first portion of said rod connector with said existingspinal rod. 14.-30. (canceled)